1. Field of the Invention
The present invention relates to a method for surface treatment such as surface cleaning, surface reforming, resist removal and etching on substrates employed for electronic parts, e.g., semiconductor devices and electronic devices, and more specifically, to an improved surface treating method utilizing jetting of ice-particles.
2. Description of the Background Art
FIG. 6 is a conceptual diagram showing a cleaning method of semiconductor wafers described in Japanese Patent Laying-Open No. 62-226629.
A container 1, e.g., with cross-sectional area of 400 .times.400 mm.sup.2 and height of 1200mm, is filled to 500mm high with liquid nitrogen 3 provided from a liquid nitrogen source 2. By blowing nitrogen gas from a diffuser tube 4 20 in the liquid nitrogen 3 at a rate of 300l/min.m.sup.2, waves of several millimeter high are produced on the surface of the liquid nitrogen 3. The nitrogen gas is provided from the liquid nitrogen source 2 through a heat exchanger 5. Meanwhile, pure water is supplied to a nozzle 6 provided at the upper part of the container 1 from a pure water source 7 under a pressure of 2.0kg/cm.sup.2 and at a flow rate of 0.1l/min, and a nitrogen gas is also provided under a pressure of 2.0kg/cm.sup.2 and at a flow rate of 8.0Nl/min. The pure water is jetted from the nozzle 6 into a mist, and becomes ice particles 8 in a moment in the liquid nitrogen. The ice particles 8 produced in this way are transferred into a hopper 10 by a screw feeder 9, for example. The ice particles 8 in the hopper 10 are next provided to a blasting device 11. The blasting device 11 is, for example, of high-pressure gas ejector type, which ejects the ice particles 8 at a rate of 0.3l/min, with nitrogen gas under a high pressure of 5.0kg/cm.sup.2 and at a flow rate of 1.0Nl/min. The jetted ice particles 8 are directed to the surface of a substrate 12, so that contaminant particles and dirts 13 are removed away from the substrate surface by sputtering effect.
However, while impurity particles, dirts or the like on the substrate can be removed by the sputtering effect of the cleaning method of the prior art employing the jetted ice particles, there exists a problem that substances of small hardness such as sticky organic substances or the like could not be removed.